At Vicarage Road, Saracens meet Ospreys in a repeat of the Anglo Welsh Cup semi final just a couple of weeks ago. If that was any kind of pre-cursor for this game, you have to worry for Sarries.

The Ospreys absolutely smashed the top seeds for these Heineken Cup quarter finals, taking full advantage of Saracens recent dip in form and totally nullifying their attacking threat. Although they got back on track with a 66 - 7 mauling of Leeds last weekend, Alan Gaffney's Saracens have shown signs recently of stalling following their sparkling start to this Heineken Cup campaign.

You can be sure that any sluggishness will be exploited to devastating effect by the Ospreys, just as they did at the Millennium Stadium. Coupled with the absence of the highly influential Kiwi Chris Jack, Saracens go in as massive underdogs and will look to another New Zealander, fly half Glen Jackson and England reject Andy Farrell to have the games of their lives to lead the team to victory.

It won't be easy up against an Osprey's side packed with a plethora of Grand Slam winning Welshmen. The side is bursting with players buoyed by their recent 6 Nations exploits and absolutely at the other end of the spectrum from Saracens in terms of belief and form. The blend of grunt and grind provided by the front 5 including the Jones brothers and Jonathan Thomas, coupled with an embarrassment of riches behind the pack make the super-charged Ospreys a fearsome prospect at the moment.

You almost run out of superlatives for the Welsh side's back line, with Hook, Henson, Parker, Byrne and the magical little man out wide, Shane Williams, providing all the components for a pacy, powerful, game breaking three quarter unit and in my mind, they must start as overwhelming favourites.

The Osprey's also have strength in depth. Most sides would sorely miss a world class scrum half in Mike Phillips but Justin Marshall, the ex All Black, should slot seamlessly in to link forwards and backs.

However, the Osprey's certainly aren't invincible. And with both sides aiming for their first ever Heineken Cup semi final, Saracens will hope that a sell out Vicarage Road crowd can help them overcome the odds.